Cited By (since 1996):19
Seaweeds, CODEN: MESED, In March 1989, the 'Exxon Valdez' spilled over 10 million gallons (ca 38 million I) of crude
oil into Prince William Sound, Alaska , USA. The spill was followed by massive clean-up using hot seawater
at high pressure as well as other mechanical and chemical techniques. We studied initial damage
and subsequent recovery in the upper margin of the Fucus gardneri assemblage on protected shores by
comparing sites that were unoiled, oiled and cleaned with hot water at high pressure, and oiled but less
intensely cleaned. F. gardneri cover averaged 80% on unoiled sites but< 1 % on all oiled and cleaned
sites 18 mo after the spill. The abundances of barnacles, littorine snails and limpets varied among sites
and species, and this variation was associated in part with differences in their life histories. F. gardneri
cover was still extremely low on oiled and cleaned sites 2.5 yr after the spill. Holdfasts that persisted
after cleaning did not resprout. F. gardneri recruitment was lowest at intensely cleaned sites, and most
recruits occurred in cracks near adults. Recruits were less abundant under adult canopies but placing
canopies over recruits did not decrease their survivorship over 5 mo. Natural weathering of tar was
rapid, with most marked patches gone in less than 1 yr. We conclude that intense mechanical cleaning
following this oil spill increased damage and slowed recovery. Such methods should be avoided if
reduction of environmental damage is the primary objective of post-spill management decisions. The
recovery of F. gardneri at its upper margin might be enhanced by devices that retain moisture and
increase substratum rugosity., ,

Growth rate and potential climate record from a rhodolith using 14C accelerator mass spectrometry,

Description

, , , Rhodoliths, free-living calcareous red algae, create large and diverse habitats worldwide. Although these plants
are abundant and ecologically important, little is known about their growth rate. We determined the growth rate for
an individual rhodolith, Lithothamnium crassiusculum, from the southern Gulf of California through 14C analysis
using accelerator mass spectrometry (AMS) to be 0.6 mm yr21. This growth rate suggests large L. crassiusculum,
which have been found with radii in excess of 6 cm, may live over 100 yr. Declines in the D14C record associated
with the large El Nin˜o events of 1957, 1982, and 1992 indicate 14C analysis may lead to identification of important
climate events in the more distant past. The ability to determine changes in past ocean circulation related to changes
in past climatic conditions through AMS 14C analysis of rhodoliths would increase the geographic range of available
climate records from the tropical oceans to the entire global ocean and potentially allow for the determination of
past climate conditions from rhodoliths in fossil beds., ,

The validity of using morphological characteristics as predictors of age in the kelp, Pterygophora californica (Laminariales, Phaeophyta),

Description

Previous studies have used stipe ring counts to estimate the age of several species in the
Laminariales. Although this method is widely accepted, it has rarely been validated. To test the validity
of aging Pterygophora californica by counting rings formed in the stipe, we sampled plants of known
age between 1.0 and 4.4 yr old and plants with a calculated age of 12 yr. For a given cohort, the number
of complete rings closely approximated the known age in years. indicating ring counts are a reliable
method for estimating the age structure of P califomica populations. However, ring counts from
individual plants of known age can vary by ± 2 yr (95 % CI), and among readers counting the same
plants by ± 1 yr (95 % CI). Single plants, there fore, could not be reliably aged by ring counts Linear
relationships between 2 morphometric measures (stipe length and stipe diameter) and number of rings
varied both within and between stands and sites, suggesting these measures are not reliable for
estimating the age of this alga in the areas sampled. Stand density may be an important factor
contributing to the variation in these morphome tric measures. Short-term (22 wk) field manipulations of
stand density showed that plants at high density (30 plants m^-2) grew faster in stipe length and slower in
stipe diameter than those at medium (6 plants m^-2) and low (2 plants m^-2) densities. Plants collected in a multi-site survey, however, showed no relationship between stand density and stipe morphology,
indicating factors other than density also influence stipe growth Short-term (22 wk) field manipulations,
which reduced ambient light levels by up to 58 %. had no significant effects on stipe morphology., , ,

The effects of insolation and grazing on populations of the splash zone alga Prasiola meridionalis (Chlorophyta),

Description

Field experiments at two sites assessed the effects of insolation and gastropod grazing on the distribution and abundance of Prasiola meridionalis Setchell et Gardner, a green alga that occurs in the upper splash zone (supralittoral) on guano-covered rocks. At site 1, a sun-exposed horizontal rock where the alga occurs seasonally and grazers were rare, blades appeared in the early spring and died back in early summer. Lack of gastropod grazers and persistence of blades in experimentally shaded plots showed that increased insolation or some associated factor (or factors) was responsible for temporal variation at this site. At site 2, the alga grew in a distinct, perennial band on a shaded vertical rock face with abundant gastropod grazers. These grazers were excluded from long vertical plots that extended from the lower portion of the P. meridionalis band down to a zone of the red alga Endocladia muricata (Postels et Ruprecht) J. Agardh more than 2 m below. The results showed that grazing set the proximate lower limit of P. meridionalis at site 2, and variation in the abundance of the alga within its zone at this site was associated with seasonal climate changes and feeding by mites. Thus, while insolation and grazing can both affect populations of P. meridionalis, their relative importance varied between sites., Cited By (since 1996):4, Seaweeds, CODEN: PYCOA, ,

, , , Geniculate coralline algae are common members of kelp forest communities. The structure provided by their stiff branches greatly influences the abundance and species composition of benthic animals and can affect associated algae by inhibiting recruitment, but the branches are themselves substrate for a large number of other taxa. However, other than qualitative observations, little is known about the within-site distribution, recruitment, and growth of these algae. We examined the distribution of the dominant corallines at a subtidal site in central California. Abundances of Calliarthron tuberculosum (Post. & Rupr.) Dawson, Bossiella californica ssp. schmittii (Manza) Johans., Calliarthron cheilosporioides Manza, Corallina vancouveriensis Yendo, and unidentifiable juveniles were determined at depths of 10, 15, and 20 m and on horizontal rock, vertical rock, and cobble. Calliarthron tuberculosum was most abundant (≤ 39% cover) at all depths, growing primarily on horizontal surfaces. Vertical surfaces and cobbles were dominated by B. californica ssp. schmittii (40 and 15% cover, respectively). These two most abundant species had the highest cover at 15 m. Calliarthron cheilosporioides and C. vancouveriensis were relatively rare (< 1% cover) and generally grew on horizontal rocks and at shallower depths. Unidentified juveniles were also rare and occurred mainly on horizontal rocks and cobbles at 20 m.
The settlement and growth rates of coralline crusts and the initiation and growth rates of young erect fronds from these crusts were determined in clearings made in the spring and fall at the three depths. Crust densities and diameters were highest at 10 m and in spring clearings. Settlement and growth tended to decrease with increasing depth. Trends were similar in fall clearings, but initial settlement was lower. Initiation and growth of fronds decreased with depth and were also higher in fall clearings. These variations in depth and substrata distribution, as well as settlement and growth, suggest there is considerable variation in the population biology between species in this group of subtidal plants., ,

The initial effects of the Santa Barbara oil spill on intertidal and kelp bed organisms were studied. Based on earlier surveys, the greatest negative biological change at a sample station after the spill was the loss of 16 plant species. However, losses in species were correlated in most cases with sand movement, and may have been related to the severe storms which occurred before and during the oil spill. Although gross species changes were not correlated with oil dosage, severe damage occurred in intertidal surf grass and barnacle populations as a result of the oil pollution. Potential long-term biological effects of the continuing pollution are discussed., , ,

Effects of shade from multiple kelp canopies on an understory algal assemblage,

Description

We examined the effects of shade from multiple kelp canopy layers (surface Macrocystis pyrifera canopy, understory Pterygophora californica canopy), both individually and in combination, on an understory algal assemblage in a central Californian kelp forest. The removal of both kelp canopies resulted in a dense recruitment of the understory brown alga Desmarestia ligulata that formed a third canopy layer, which significantly decreased bottom light and the abundance of understory red algae. We subsequently created an additional canopy treatment by removing this third canopy layer. In general, the understory red algae fluctuated seasonally with winter swell intensity, changes in kelp canopy cover, and grazing; and although species richness increased significantly with increased bottom light, red algal bottom cover did not respond significantly to the canopy clearings until 2 yr after the canopies were initially cleared. Red algal cover within the Pterygophora canopy treatment was similar to that in the control treatment. In the absence of Pterygophora, the Macrocystis canopy treatment and 'no canopy' treatment were found to have greater red algal cover and species richness. Individual understory species were rare, which resulted in small effects sizes and thus low statistical power. However, when grouped post hoc, according to how they responded to the canopy clearings (i.e. response groups), we were able to detect canopy treatment effects as much as 1 yr earlier. This method identified that some understory red algae adapted to areas of canopy removal (light-adapted), and others adapted to a variety of light regimes (shade-tolerant). We were able to classify the light-adapted algae into 2 subgroups: the high-light species and the intermediate-light species. Although this method of grouping was done post hoc, our results indicate that it may provide the clearest assessment of how understory algae respond to shading from kelp canopies., Cited By (since 1996):40, Seaweeds, CODEN: MESED, ,

Management of artificial reefs designed to support natural communities,

Description

, , , Pendleton Artificial Reef (PAR) was designed to determine the potential of artificial reefs
for mitigating possible losses of kelp-reef habitat caused by operation of coastal power plants.
In an attempt to alter natural succession on PAR, massive transplants (hundreds ofindividuals)
of two kelp species (Macrocystis pyrifera and Pterygophora californica) and juvenile
abalone (Hatiotis rufescens; thousands of individuals) have been conducted. Although the
PAR site once supported a kelp forest, kelp transplant efforts were not successful, principally
because of intensive grazing by two herbivorous fish; halfmoon and opaleye. Similarly, abalone
transplantation was not successful, probably because of crab (Cancer spp,) predation
and lack of suitable food. In hindsight, these attempts at manipulating succession may have
been successful if the densities of grazing fish were artificially reduced, if abalone additions
were delayed until more algae were present, and if abalone transplant techniques were used
that would minimize predation. Management of artificial reefs should not be limited to only
initial planning, but should also consider manipulating succession after placement. Initial
planning should consider the physical and chemical environment (past and present), the
biological environment (e,g" location with respect to surrounding communities that could
influence dispersal and/or attraction of desirable or undesirable organisms), the design, size,
and configuration of the artificial habitat relative to local natural habitats, as well as other
factors that affect the quality of the subhabitats (e,g" construction material, interstitial volume,
rugosity of the substratum). After an artificial reef has been constructed, there are additional
factors that will influence community development. These include timing of reef installation
(e.g., availability of spores and larvae to colonize the reef) and possible post reef placement
management techniques (e.g., transplantation or removal of select species to alter natural
succession). Our general conclusions with respect to succession on PAR is that although initial
reef planning factors are important, these are subordinate to reef management techniques
after installation (e.g., manipulation of prey/predator densities; addition or removal of select
species to direct and/or disturb community succession)., ,

Despite the recognition of the usefulness of BACI designs for assessing environmental impacts, there are few examples because of the need for repetitive sampling over long time periods. Our examination of the application of a BACI design to detect the impacts of elevated seawater temperature from the Diablo Canyon Power Plant in central California on rocky intertidal communities showed statistically significant changes in a large percentage of the species analyzed. The statistical power of the analysis resulted from both the large numbers of surveys before and during plant operation and from other design features that made the study resilient to the effects of two "100-year" storms, several ENSO warming events, and the highly variable nature of the impacts. The large data set from the study required the development of decision rules for determining the appropriate surveys, stations, and species to analyze. BACI analyses were used to test the effects of the thermal plume on 47 algal and 50 invertebrate data sets. There were statistically significant effects for 79% of the algal and 60% of the invertebrate data sets. At the impact sites, there was a loss of cover by foliose algae and increases in crustose forms. Many invertebrates, particularly grazing gastropods, increased in abundance. Multivariate analysis of the community showed that there was continual change in impact sites that lasted throughout the study. The nature, magnitude, and spatial extent of the effects identified from the study are being used to determine appropriate plant modifications or mitigation for the effects of discharge. This study illustrates many of the problems in analyzing environmental effects and clearly demonstrates the need for long-term monitoring. This was especially true for this study, where storms and ENSO events affected our ability to analyze data from some of the stations, and points out the importance of having redundancies built into monitoring programs. The complex interactions among the direct effects of the discharge, indirect community-level effects, and variation due to oceanographic conditions provide useful insights for planning impact assessments and other ecological studies, and help contribute toward science-based regulation and management., Cited By (since 1996):9, CODEN: ECAPE, ,

Benthic succession on an artificial reef designed to support a kelp-reef community,

Description

, , , Pendleton Artificial Reef (PAR) was constructed to determine the potential of artificial
reefs to mitigate for possible losses of kelp-reef habitat resulting from operation of coastal
power plants. Placed in August 1980, PAR consists of eight boulder modules (some topped
with cobble) on a featureless sand bottom at a depth of 13.1 m below MLLW. We studied
benthic succession on PAR from September 1981 through August 1983 using a point quadrat
sampling technique to describe abundances and vertical distribution of organisms. During
this period, small foliose and filamentous algae growing on or over other organisms accounted
for 56% of the overstory cover. Cryptoarachnidium (a sediment fixing, encrusting ectoproct)
and barnacles accounted for 66% of the understory cover. Cryptoarachnidium was particularly
abundant on all modules, while algal turf cover was highest on modules constructed primarily
of boulders. On module crests where light and water motion were highest, algal turf was
greatest and negatively correlated with erect ectoprocts that were greatest on the slopes of
modules. Since erect ectoprocts may inhibit algal colonization and were most abundant on
the slopes, we suggest that light, turbidity, and competitive interactions with erect ectoprocts
limit the comparatively high cover of algal turf to the module crests. Cover of algal turf was
also greatest during periods of clear water in late fall and early winter, while erect ectoproct
cover increased during the study period. Cryptoarachnidium cover increased rapidly during
the first year after reef placement and stabilized during 1982-1983. Barnacles were the only
organisms to show a decline in abundance during the study period. PAR has been in place
over 3 years, but relatively to a local natural reef, is still dominated by early successional
species. This phenomena appears to result from a number of factors, but especially environmental
conditions at the time of reef placement and the isolation of PAR from other shallow
reefs in the area., ,

Recreational SCUBA diving has greatly increased in the past 20 years and has potential to cause significant disturbances to subtidal reefs. While diver disturbance on coral reefs has been assessed in a number of studies, disturbances in temperate kelp forests have not been previously examined. We estimated diver disturbance in southern Monterey Bay giant kelp, Macrocystis pyrifera, forests by following 42 divers in summer 1997 and recording their activity. During a 0.5 hour dive, the average diver contacted the bottom 43 times, touched 4 animals, and detached 2 algal blades. An estimated 65,000 diver-days are spent in these kelp forests every year, resulting in a potential loss of 130,000 algal blades and considerable benthic disturbances. The effects of these impacts and mitigation for them should be considered in proposals to establish and manage marine protected areas., Cited By (since 1996):2, Ecology,
Seaweeds, ,

Living rhodolith beds in the Gulf of California and their implications for paleoenvironmental interpretation,

Description

Subtidal surveys in the southwestern Gulf of California indicate that rhodolith beds are widely distributed, major sources of carbonate sediments, and habitats of high biodiversity. Beds with abundant branched rhodoliths ranging in size from 2 to 10 cm (longest dimension) have been found in two main types of environments: (1) gently sloping, subtidal soft bottoms with moderate wave action (wave beds; 2 to 12 m deep), and (2) relatively level bottoms in channels with tidal currents (current beds; below 12 m). Large individuals (to 11 cm) with up to 1 cm thick, densely packed branches are also found dispersed among sand and cobbles on more wave exposed shores. The relative abundance of fruticose forms and the sphericity and branch density of individual thalli are generally higher in wave beds than in current beds. Morphology within wave beds varies along gradients of water motion, with higher branch densities, more apical branching, and more branch fusions present as water motion increases. The extent to which these morphological differences represent different taxa is being evaluated. The abundance of rhodoliths in Pliocene and Pleistocene carbonate deposits and modern sediments indicates that this community has long been an important feature of nearshore environments in the Gulf. Our results suggest that measurements of a combination of morphological characters in populations of fossil rhodoliths, combined with detailed, small-scale stratigraphic analyses, may provide good estimates of paleoenvironmental conditions., Cited By (since 1996):6, Seaweeds, ,

Restoration techniques for Macrocystis pyrifera (Phaeophyceae) populations at the southern limit of their distribution in Mexico,

Description

Following the 1982-83 El Nino, Macrocystis pyrifera (L.) C. Agardh, forests disappeared throughout their range in Baja California. The giant kelp forests subsequently recovered within this range except at their extreme southern limit, a region encompassing 50 km of coastline with a former giant kelp standing stock of 28,000 wet tons. Two techniques were tested to restore these forests: juvenile transplantation and seeding with sporophylls. For transplanting, juvenile M. pyrifera sporophytes were attached to Eisenia arborea stumps seasonally over a two-year period. Average survival of transplants ranged from 7% in spring to 41% in winter. After two years, the average number of basal fronds per plant increased from 2 to 64 per plant and surface fronds from 0 to 34 per plant. Average frond growth rate of the transplants ranged from 8.1 cm day -1 in summer to 10.8 cm day -1 in winter. No significant differences in growth rate were found among treatments (seasons) for the transplants, but control plants showed a seasonal variation, with higher frond growth rates in winter (13.3 cm day -1) and spring (9.3 cm day -1) and lower in summer (4.4 cm day -1). The seeding technique was tested in a fully orthogonal-block design with three factors with two levels (factors: ± sporophylls addition, ± Eisenia arborea and ± understory algae). Macrocystis pyrifera recruitment occurred only in treatments with added sporophylls. The highest recruitment occurred where all algae were removed from the bottom, followed by the treatments without understory algae but with Eisenia arborea. This results suggest that a lack of spores and the presence of understory algae were the main factors inhibiting Macrocystis pyrifera recruitment in the area. Lower sea water temperatures and high nutrient concentrations occurred in spring and high temperatures and low nutrients in summer suggesting, as in southern California, an inverse relationship between these two factors. The results suggest a combined approach of transplanting juveniles and seeding during spring would be most effective for restoring the M. pyrifera forests., Cited By (since 1996):22, CODEN: BOTNA, ,